1. Field of the Invention
The present invention relates to a new and improved dosing or metering method and apparatus for the delivery of predeterminate or determinable quantities of fiber flocks per unit of time by means of two feed devices arranged at the lower end of a fiber flock filling or feed chute and which two feed devices form therebetween a conveying or feed gap.
2. Discussion of the Background and Material Information
A dosing method and apparatus of this type is disclosed, for instance, in Great Britain Patent No. 735,172 and the cognate Swiss Patent No. 313,355, granted Apr. 15, 1956. A similar method and apparatus is also known from the German Published Patent No. 3,713,590, published Oct. 8, 1987, but additionally uses an opening or opener roll located beneath the feed rolls forming the feed devices.
Further examples of such equipment have been disclosed in German Patent No. 196,821, granted Jun. 30, 1907, German patent No. 3,151,063, published May 24, 1984 and Japanese Patent Document No. 62-263,327, dated Nov. 16 1987.
During the manufacture of yarn there are usually blended or admixed mixtures of different fiber-like constituents, that is to say, fibers of different origins, types, quality, color or other attributes, in order to produce fiber blends which are subsequently carded and delivered to the further spinning operations.
The blending or mixing of the fibers can be accomplished in that the different types of fibers are filled into associated filling or feed chutes and deposited upon a revolving conveyor belt or band by the feed rolls located at the lower end of the filling or feed chutes. As a result, there is produced a continuous layered or sandwich structure upon the revolving conveyor belt or band which is then delivered to an opening roll. This opening roll extracts individual fiber flocks from the layered structure and promotes good admixing or blending of the different fibers of the different layers which were previously deposited upon the conveyor belt. It is possible to determine the momentarily desired proportion of the individual fiber constituents by controlling the rotational speed of the individual feed rolls.
Efforts have been expended to control the filling height of the fiber flocks in the individual filling or feed chute such that this filling height remains essentially constant, so that with a constant fill height and predetermined rotational speed of the feed rolls the momentarily required fiber quantity is dosed or deposited upon the revolving conveyor belt.
With these prior art dosing methods and dosing apparatuses it is only possible to achieve to a limited extent the momentarily prescribed dosed quantity of fiber flocks. The heretofore known apparatuses only take into account relatively inaccurately fluctuations in the density, the fill height and the degree of opening of the fiber flocks.
The presence of such inaccuracies promoted the use of balance feeds where the individual constituents are weighed prior to blending. However, such type of equipment is relatively complicated and expensive.